In order to control part quality and minimize cycle time, it is necessary to cool a die during a die casting operation. Typically, water or oil have been used as a coolant or cooling medium inside cooling channels in the dies. The coolant extracts heat from the die and the casting material during the die casting cycle. Attempts have been made to control the amount of flow of the coolant to control the amount of heat extracted from the die. In some cases, the flow of coolant has been stopped and restarted to control heat extraction.
The goal in using the coolant is an attempt to attain steady state temperatures to cool the die so the cast material cools in a desired amount of time. Controlling the amount of heat extracted by controlling the amount of flow of the coolant works satisfactorily with castings having a consistent wall thickness. However, undesirable results are obtained where the casting wall thickness varies from thick to thin, or with complex shapes. In this situation, inconsistent cooling occurs where the coolant cools the thin areas quickly and the thick areas slowly. The inconsistent cooling results in cold die casting defects such as cold flow and hot die casting defects such as soldering. Additionally, an area of the casting which is needed to feed pressure to a thicker section of the casting can be prematurely cooled. As a result, shrink porosity can be present in the thicker section of the casting.
It would be desirable to produce a system for thermal management of a die wherein control of heat extracted is maximized.